Agile Performance Testing - Testing Experience

To accomplish performance testing, we need to engage in a careful,
controlled process of measurement and analysis. It is critical
to understand that the aim of performance testing is not to find
bugs, but rather to identify bottlenecks. Ideally, the software under
test should be stable enough so that this process can proceed
smoothly.
Most large corporations have performance testing and engineering
groups today, and performance testing is a mandatory step
to get the system into production. However, in most cases, it is
pre-production performance validation only. Hence there seems
to be a need for an efficient way to do performance testing. Most
often it is believed that agile introduces chaos and is therefore not
suitable for performance testing, which is a careful, controlled
process. This article unfolds the fact that doing performance testing
in a more agile way may increase its efficiency significantly.
The teams practicing XP always had working software due to the
continuous integration practices. They also have a suite of automated
tests. XP
coupled with agile
planning and automated
performance
regression tests is a
big step towards
agile performance
testing.
Let’s look at how some of the agile principles like test early, continuous
improvement and collaboration can be applied to performance
testing.
Test Early – Early Performance Testing
The main obstacle here is that many systems are generally colossal,
if there are parts - they don‘t make much sense separately.
However, there may be significant advantages to test-drive
development. If you can decompose the system into components
in such way that we can actually test them separately for performance,
then all that we need to do is to fix integration issues, if
any, when we put the system together. Another problem is that
large corporations use a lot of third-party products, where the
system usually seems to be a „black box“ and cannot be easily understood,
which makes it more difficult to test effectively.
Though it is well understood that it is better to build performance
right up front, i.e. during the design stage, and pursue performance-related
activities throughout the whole software lifecycle,
unsurprisingly quite often performance testing happens just before
going live within a very short timeframe allocated for it. Still
Agile Performance Testing
© iStockphoto.com/AYakovlev
by Sowmya Karunakaran
approaching performance testing formally, with a rigid, step-bystep
approach and narrow specialization, often leads to missing
performance problems altogether, or to a prolonged agony of
performance troubleshooting. With little extra effort, by making
the process more agile, efficiency of performance testing increases
significantly – and these extra efforts usually pay off multifold
even before the end of performance testing.
Iterative Performance testing
This is crucial for success in performance testing, and an agile
environment is surely conducive for this. For example: A tester
runs a test and gets a lot of information about the system. To be
efficient he needs to analyze the feedback that he got from the
system, make modifications to the system and adjust the plans if
necessary. The cycle below, if done in an iterative fashion until the
system under test achieves the expected levels of performance,
will yield better results and also serve as a baseline to perform
regression tests.
Performance Optimization (Continuous Improvement)
Performance testing becomes meaningless if it is not complemented
with performance optimization. Usually when the performance
of a system needs to be improved, there are one or two
methods where all the time is spent. Agile optimization works by
garnishing existing unit tests with a timing element.
The process involves six easy steps:
1. Profile the application
2. Identify the bottlenecks
3. Find out the average runtime of the methods and create a
baseline.
4. Embellish the test with the desired runtime.
5. Refactor / optimize the method.
6. Repeat until finished.
However, care must be taken to ensure that the data used for tes-
64 The Magazine for Professional Testers www.testingexperience.com